The present invention relates to plastic-bonded explosive (PBX) compositions, and, more particularly, to an improvement in such PBX compositions which comprises incorporating therein from about 0.0025 wt. % up to a value of less than 2 wt. % of fibrillated polytetrafluoroethylene (PTFE) whereby the coherency of the resulting composition is enhanced, and the resulting formulation is extrudable and formable into desired shapes, such as, for example detonating cords. The present invention is particularly useful in improving the extrudability and formability of PBX formulations in which the nitrocellulose component is a non-dynamite grade, i.e., low-viscosity grade, nitrocellulose. The present invention also relates to a process for improving the tensile strength and the elongation properties of such PBX compositions in which a grade of nitrocellulose other than dynamite grade nitrocellulose is employed as a binding agent which comprises incorporating into the composition from about 0.0025 wt. % up to a value less than 2 wt. % of fibrillatable PTFE, and then mixing the composition with sufficient shearing action to fibrillate the PTFE and distribute it uniformly throughout the finished composition.
Nitrocellulose of a "high" viscosity is normally required when forming PBX compositions, as described, for example, in U.S. Pat. Nos. 2,992,089; 3,317,361; 3,400,025; and 3,943,017. Such "high" viscosity nitrocellulose is commonly referred to as "dynamite grade nitrocellulose" or "blasting soluble nitrocellulose" in contrast to industrial nitrocellulose grades which are inherently weaker because of a lower relative tensile strength and bonding strength. The coherency of PBX compositions, i.e., formulations, which are based on a non-dynamite grade nitrocellulose, makes them generally not formable into useful explosive products using conventional pressing, molding, sheet forming, and extrusion techniques.
It has now been found according to the invention that PBX products can be successfully formulated with non-dynamite grade nitrocellulose when fibrillated PTFE resin is uniformly distributed throughout the composition.